1. Field of the Invention
The present invention relates to recording of information on an optical recording medium having a plurality of recording layers, and more particularly, to an optical recording method, an optical recording apparatus, a micro CPU device, and a computer program, which can save a test time for recording information.
2. Description of the Related Art
As known in the art, in an optical recording apparatus for recording data on an optical recording medium such as a known DVD by the use of a laser beam, when recording data on a predetermined recording medium, a recording condition suitable for the recording medium is generally obtained by performing a test recording operation to a test recording area in the recording medium before actually recording data.
However, with increasing requirement for increase in speed and capacity of the optical recording apparatus, when data are recorded on a multi-layered optical recording medium having a plurality of recording layers, it is necessary to obtain recording pulse conditions corresponding to the recording layers, respectively, due to differences in physical characteristics such as recording sensitivity, light reflectance, and thermal conductivity between the recording mediums.
As a known technology for obtaining the recording pulse conditions, as shown in FIGS. 15 and 16, a method is generally used, in which a data table recording the recording pulse conditions for excellently recording data on the respective recording layers in accordance with conditions such as a recording speed every type of recording mediums is stored in advance in a memory of a recording drive (optical recording apparatus) and the recording pulse conditions corresponding to the types, the recording layers, and the recording speeds of the recording medium are read out and set from the data table at the time of actually recording data on the recording medium, thereby recording the data.
In consideration of individual difference or non-uniformity of the recording drive or dependency of a laser on a temperature, a method of adjusting only a condition of the recording laser power at the time of a test recording operation performed before a data recording operation is also generally used.
However, in the known art, it is not possible to satisfactorily cope with the non-uniformity in characteristics of the recording medium and the optical recording apparatus, which the recording laser power cannot compensate for. In addition, it is not possible to satisfactorily cope with “unknown types of optical recording mediums” such as optical recording mediums not previously memorized in any recording apparatus and optical recording mediums (which partially cope with them in the form of firm-up) come to the market after an optical recording apparatus comes to the market.
Therefore, as a recording method of a multi-layered optical recording medium having a plurality of recording layers, for example, a technology disclosed in Japanese Unexamined Patent Application Publication No. 2003-178448 is known.
In the technology, a strategy design is carried out so as to more rapidly cool an outer recording layer than the innermost recording layer as seen in the direction of an incident beam. In the laser power control, the peak power and the bottom power are varied by the use of the optimum power control (OPC) and are repeated until evaluation parameters (for example, modulation, error rate, and jitter) reach predetermined values. In the pulse width control, the bottom period of time, the cooling period of time, and the like are elongated to enhance the cooling ability, thereby improving recording quality for the innermost and outer recording layers. The following patent documents provide additional background:
Japanese Unexamined Patent Application Publication No. 2003-178448
Japanese Unexamined Patent Application Publication No. 2005-100610
Japanese Unexamined Patent Application Publication No. 2003-22532
Japanese Unexamined Patent Application Publication No. 2004-171740
Japanese Unexamined Patent Application Publication No. 2004-247024
PCT Publication WO2002-029791
However, in the technology disclosed in JP-A 2003-178448, since the test recording operation is performed to the respective recording layers by repeating the peak power and the bottom power in the laser power control and the bottom pulse and the cooling pulse in the pulse width control are repeated until the optimum recording condition, there is a problem that it takes time to obtain the optical recording condition of each recording layer. Since it takes time to adjust the recording condition of each layer, the increase in the number of layers causes elongation of the whole test recording time.